Shakespeare’s King Claudius opines in Hamlet, “How dangerous is it that this man goes loose! Yet must not we put the strong law on him.” Indeed, “this is a question to which the courts, lawyers, mental health professionals and the general public all want to know the answer” (Hucker, 2005, p. 1). Violence involves a host of dynamic, static, and behavioral factors. Violence is complex and perplexing, and it weaves a tangled web. For example, some studies believe “an individual’s history of violence is the single most predictive factor of violence and the history of substance abuse the second most predictive factor” (Ackerman, 1999, p. 147). Yet, a 2012 government report by the Defense Science Board (DSB) Task Force Report: Predicting Violent Behavior states that “targeted” violence cannot be reliably predicted. This contrast in perspective of an individual’s history of violence juxtaposed with a perpetrator’s targeted violence speaks to the multifaceted aspects of violence risk assessment.

Shakespeare’s King Claudius opines in Hamlet, “How dangerous is it that this man goes loose! Yet must not we put the strong law on him.” Indeed, “this is a question to which the courts, lawyers, mental health professionals and the general public all want to know the answer,” (Hucker, 2005, p. 1). The intent here is to present a macro perspective of violence from which to further explore the complex correlations of violent human behaviour.

The definition of violence holds considerable variations. Violence may range from playground fights to contact sports, robbery, murder, and forcible rape. A definitional perspective is important, for one man’s freedom fighter is often another man’s terrorist inflicting indiscriminate violence on innocent people (Tolan, 2007, p. 5). For example, the United States government contends that Nidal Hasan, the former Army psychiatrist and convicted Fort Hood mass murderer, is merely a perpetrator of workplace violence, while others clearly see him as a murderous, radicalized terrorist. Furthermore, in the literature, there is discussion detailing the fine distinction between violence and aggression (Meloy, 2004). While the granulation of violence and aggression is useful, for the purposes here, violence is defined as aggressive-assaultive behaviour that results in physical or psychological abuse or injury, and/or threatening activities directed towards others or one’s self.

Types of Violence

Not all violence and aggression are the same. Instrumental aggression or violence has the purpose of achieving a goal rather than merely inflicting pain and/or harm. Hostile violence has the specific purpose of inflicting harm, pain, and/or suffering. The difference between instrumental and hostile violence essentially lies in the motivation and psychology behind the behaviour (Englander, 2007, p. 2). In essence, the definition of violence depends upon whether the motivation is to achieve a goal (i.e. instrumental) or to intentionally inflict pain/suffering (e.g. hostile).

Mawson (1999) describes a third kind of violence he calls impulsive or stimulus-seeking violence where the “perpetrator craves dangerous risky encounters and/or is under the influence of drugs which is behaviour common to those impulsively engaging in activities seeking intense stimulation”). Interestingly, designating categories of violence (e.g. instrumental, hostile, or stimulus-seeking) appears easier than it is. One man’s violence may be another man’s sport.

Individual’s History of Violence

Ackerman writes, “an individual’s history of violence is the single most predictive factor of violence and the history of substance abuse the second most predictive factor,” (p.147). Wachtel (2012 p. 1) agrees, in part, with Ackerman:

By far, past violence is the best static predictor of future violence. On its own, it is still not great at predicting a future violent act (for example, a person who has murdered someone in the past is actually not all that likely to murder someone again in the future). But, when past violence is added to a host of other static factors, a clinician's predictive ability rises dramatically. In fact, at the present time, conducting a risk assessment using a static factors method can predict violence (or non-violence) about 65-70% of the time. Still not great, but much better than the 33% that the Barefoot v. Estelle Court thought was acceptable.

Hucker (2005) notes that a violent history is one of the most powerful indicators of the potential for future violence. Hucker also observes that, in addition to a violent history, the nature of the violence itself (e.g. types of victims and environmental and contextual issues) is a key component to consider regarding efforts to forecast or predict the probability of violence. Attempting to forecast or predict the probability of violence includes other factors as well as demographic characteristics, traumatic events (physical and/or psychological), and low socioeconomic conditions (Loeber et al., 2005, p. 1074).

The task of forecasting the probability of violent behaviour (e.g. dangerousness) subsumes a constellation of interactive factors. Research findings are often mixed. For example, Warren, Mullen, Thomas, Ogloff, & Burgess, (2008) dispute claims that uttering threats are not predictive of subsequent violence. Rather, their studies reveal that high rates of assault and even homicide rates do follow in the wake of threats to kill (p. 599).

Bullying

With respect to threats of violence, Bender & Lösel (2011) note that bullying at school is a predictor of not only delinquency, but violence and other anti-social behaviour in adulthood. Yahner, Dank, Zweig, & Lachman (2015) report in their work that there is a substantial co-occurrence of all types of teen dating violence and bullying. Teens who commit and/or have experienced physical, psychological, or cyber bullying are likely to commit/face physical and sexual dating violence, as well as being subjected to psychological and cyber dating abuse (p.1079).

Learned Violence

Violence may find its genesis in learned behaviour. According to Males (1998), "the youth culture of violence is the adult culture of violence" (p.1). Learned behaviour manifests itself as violence. "Nearly 10 times as many children die at the hands of their parents as at school. The tradition of learning by example has rarely had such tragic consequences” (Nemecek, 1998, p. 16). T. D. Goldsmith (2013) too contends that studies suggest violent behaviour may stem from situational and individual factors whereby abusers learn their violent conduct and actions from family, community, and other cultural influences.

Learning by observation and imitation was the subject of study in the 1960s by Albert Bandura. Bandura held that people learn by observing and imitating others. Learning consisted of more than just punishment and rewards. Bandura’s “Bobo Doll” research underscores the idea that learning is not just about punishment and rewards, but incorporates observation and imitation as well.

Bandura’s research involved children watching an adult beating up a non-threatening clown doll with a big grin on its face. When it was the children’s turn to play with BoBo, the clown doll, children who observed an adult battering the doll were likely to show similar aggression towards the doll, themselves. The children were imitating (i.e. modelling effect) the adult behaviour. The children kicked the doll, hit it, and threw it into the air. The children also came up with new ways to assault the doll, such as aiming a toy gun at it. The children who observed the non-aggressive adult exhibited far less aggression towards the BoBo doll, along with the children who did not have any experience of watching an adult model (Bartol & Bartol 2005, p. 264).

Bartol and Bartol (2004) note that Bandura’s work is replicated in numerous studies underscoring the “modelling effect.” It is suggested that viewing media violence presents a modelling venue that has an influence on real-life violence. Grossman and Degantano (1999) describe how military training tactics, techniques, procedures involving violence, weapons, and killing are found in violent video games today, ultimately providing a violent modelling venue.

Nevertheless, literature is divided on the effects of violent media on aggressive and violent behaviour. Bartol and Bartol (2008, p. 131) point out that the largest body of media violence research focuses on TV violence. However, the preponderance of more recent research involves violent video games (Murray, 2008). Anderson (2004) and Anderson et al. (2008) suggest that heavy exposure to violent video games is linked with an increase in aggressive behaviour.

More recently, Anderson et al. (2010) write, “evidence strongly suggests that exposure to violent videogames is a causal risk factor for increased aggressive behaviour, aggressive cognition, and aggressive affect and for decreased empathy and prosocial behaviour” (p. 151). Willoughby, Adachi, and Good (2012) found in their study that sustained violent video game play was significantly related to steeper increases in adolescents’ trajectory of aggressive behaviour over time, and that greater violent video game play predicted higher levels of aggression over time, after controlling for previous levels of aggression (p. 1044).

Bartol and Bartol (2008) feel that if there is a research consensus emerging, it is that violent video games may be one risk factor concordant with the other risk factors that may contribute to antisocial or violent behaviour (p. 133). For example, violence exposure may be a risk factor. Pozios, Kambam, and Bender (2013) note that “the surgeon general, the National Institute of Mental Health, and multiple professional organizations — including the American Medical Association, the American Psychiatric Association, and the American Psychological Association — all consider media violence exposure a risk factor for actual violence" (p. 1).

Substance-Related Disorders and History of Violence

Risk assessment studies call attention to the connection between one’s history of substance-related disorders and one’s history of violent assault. Studies state that the “far greatest support for a link between substance use and violence involves alcohol” (Kilpatrick, Acierno, Resnick, Saunders, & Best, 1997; Substance Abuse and Mental Health Services Administration [SAMHSA], 2001). When one addresses substance use disorders (e.g. alcohol) and violence, there are multiple variables and factors.

There is a range of factors to consider when creating a complex analytical task to determine the exact causative effects and to explicitly identify risk factors. Large epidemiological studies looking at comorbid offenders show that substance use correlates with violence. Studies find that this correlation of substance use with violence “is true for people with mental illness and those without mental illness,” (Johns, 1997 p. 239).

The correlation of alcohol to violence either in small or large quantities is compelling particularly with respect to what once was described as pathological intoxication. Pathological intoxication, a term that is no longer found in the DSM, is a disorder that stems from alcohol use resulting in violence. Schlesinger (2007) observes that this disorder has been recognized for about a hundred years. Pathological intoxication is an “idiosyncratic reaction to small amounts of alcohol often culminating in extreme violent behaviour”(Schlesinger, 2007, p. 5-6). According to Bartol and Bartol (2005), the alcohol-violence connection to extreme violent behaviour appears to be strongest in the United States (p. 517).

Impulsivity

Studies report an association between impulsivity and violence. Impulsivity is defined as “the tendency to pursue potential rewards without attending to or considering the consequences,” (Kring, Davison, Neale, & Johnson, 2007, p. 402). Flannery, Vazsonyi, & Waldman (2007) note that impulsivity is one of the most important dimensions for predicting violence. This concept is magnified when coupled with hyperactivity, poor behavioural control, and attention issues. Toch (1969), Berkowitz (1970), and Zillman (1979, 1983) contend that due to impulsivity, people become incapable of appreciating the consequences of their violent acts when experiencing states of high emotional arousal. It seems that high levels of emotional reaction are associated with impulsivity (Toch, 1969; Berkowitz, 1970; Zillman, 1979; Zillman, 1983. Hart and Dempster (1997) contend that a salient and central characteristic of a psychopath is impulsivity.

Psychopathy

Hare (1993), in his book Without Conscience, describes psychopaths as social predators who charm, manipulate and ruthlessly plow their way through life" (p. xi). The topics of psychopathy, risk assessment, and violence are not unfamiliar to the forensic community. The forensic application of psychopathic risk assessment predictive of future violence has increased over the last decade according to the research of Walsh & Walsh (2006).

Studies found in the literature emphasize the relationship between psychopathy and violent behaviour. This relationship is established. The research of Walsh, Swogger, and Kosson (2009) underscores this linkage:

The present study provides further evidence for a relationship between the inter-personal traits of psychopathy, and violent behaviour. Such evidence contributes to our understanding of differences across classes of violent offenders and may have implications for the identification, management, and treatment of individuals who engage in instrumental violence (p.1).

Psychosis and Violence

The association between psychosis (e.g. schizophrenia) and violence enjoys debate in the research literature. Taylor (2008) conducted a comprehensive literature review drawing on new empirical data and other major reviews. Taylor posits that, “almost all sound epidemiologic data on psychosis and violence dates from 1990.” Taylor’s (2008) data does indicate that “there is consistency on a small but significant relation between schizophrenia and violent acts” (p. 647). In a systematic review, Fister (2009) identified 20 studies relevant to psychosis and violence. Fister concluded that “schizophrenia is indeed linked to violence, but mostly through substance misuse” (p. 442).

Cognitive Aspects Violence

Bandura studied the behaviour of individuals engaging in destructive activities towards others, describing it as “moral disengagement” behaviour. People do not generally act out destructively unless they have a mechanism to morally justify their actions to themselves and others (Bandura, 2004). Moral disengagement encompasses the ways one mitigates, justifies, neutralizes, or eliminates inhibitions or moral constraints connected to committing acts of crime or violence (McAlister, A., Bandura, A., & Owen, S., 2006).

Bandura holds that people use moral disengagement techniques such as cognitive reconstruction, cognitive redefinition, and dehumanization for justifying and legitimizing despicable acts and barbaric conduct. In essence, using their cognitive abilities to sanctify violence (Bandura, 2005). Hancock, Tapscott, and Hoaken (2010) examined individual cognitive abilities of violent offenders. According to Hancock et al, "offenders were found to have broad and pervasive dysfunction in their executive abilities" (p. 338).

Neurocriminology

The biological factors in the literature often allied with violence are frontal lobe deficits, neurological trauma, neurotransmitter abnormalities, and behavioural genetics. With the availability of new neuroimaging techniques, researchers are able to identify areas of the brain that may be dysfunctional in criminals who are aggressive and violent. Bufkin & Luttrell (2005), in reviewing 17 neuroimaging studies, uncovered neurologically specific areas in the prefrontal cortex and the medial temporal regions associated with aggressive and/or violent behavioural histories, especially impulsive actions.

The advances in brain imaging continue to open the doors of neurocriminology. Aharoni et al (2013) in their research explain how brain imaging accurately predicts the likelihood of a criminal getting re-arrested. Raine (2014), using the brain imaging technique of position-emission tomography (PET), discovered reduced prefrontal cortex functioning in murders. Raine is credited with being the first to use brain imaging to study the brains of violent criminals (i.e. murders) comparing the images of “normal” people with violent criminals.

PTSD and Violence

The association of PTSD with violence is covered in the research literature especially as it impatcs military and veteran communities. Devor (2015) succinctly reviewed studies of military personnel and veteran studies relating to PTSD, anger, hostility, and violence. They found consistent results:

...indicating that levels of anger and hostility are larger among military personnel with PTSD compared to military personnel without PTSD (Beckham, Feldman, Kirby, Heertzberg, & Moore, 1997; Castillo, Fallon, Baca, Conforti, & Qualls, 2001; Frueh, Henning, Pellegrin, & Chobot, 1997; Kubany, Gino, Denny, & Torigoe, 1994). Veterans with PTSD are more prone to commit hostile acts as compared to veterans without PTSD (Beckham et al., 1997; Lasko et al., 1994; McFall, Fontana, Raskind, & Rosenheck, 1999). A study conducted by Kulka et al. (1988) found that Vietnam veterans with PTSD reported being involved in an average of four times more acts of violence per year compared to veterans without PTSD. Beckham et al. (1997) found that Vietnam combat veterans with PTSD reported 20 times more acts of violence in one year as compared to combat veterans without PTSD or compared to civilians. Lasko, Gurvtis, Kuhne, Orr, and Pitman (1994) suggested "increased aggression in war veterans is more appropriately regarded as a property of PTSD, rather than a direct consequence of military combat" (p. 373). It appears as though these acts of violence have a ripple effect that span outward beyond the individual with PTSD, but affect the entire community.

Acts of violence are all too often displayed on the home front. Veterans with PTSD are more likely to express anger and physical aggression with a spouse or intimate partner as compared to veterans without PTSD (Glenn et al., 2002; Jordan et al., 1992). This has led to a strong consensus in the military community that anger and aggressive behaviors are major points of interest to be addressed (Biddle, Elliott, Creamer, Forbes, & Devilly, 2002; Calhoun et al., 2002; Jordan et al., 1992) (p.25).

While PTSD and violence is of significant concern to the military community, PTSD symptoms are widely reported within the research literature following the commission of violent crime. Lad (2013) chronicles:

Within the research literature cases where individuals experience symptoms of post traumatic stress following the perpetration of homicide have been widely reported (Harry & Resnick, 1986; Kruppa, 1991; Papanastassiou, Waldron, & Chesterman, 2004). Within a prison sample of 80 homicide offenders Pollock (1999) found that over half of the sample met DSM IV criteria for post traumatic stress disorder(PTSD) associated with both their index offence as well as other events.

Ninety-five percent of sample that experienced PTSD symptoms in relation to their index offence were deemed to have enacted reactive violence (impulsive), rather than instrumental violence (pre-meditated). Also, Crisford, Dare, and Evangeli (2008) found that severe offending, such as homicide was more likely to predict PTSD symptoms, compared to less severe offending i.e. threats to kill. (p. 788)

Risk Assessment and Violence

Risk assessment in the area of violence is dichotomized by the “clinical” and “actuarial” perspectives where the actuarial approach requires no clinical input, but rather, translates records into a risk score. Clinical methods, on the other hand, rely on clinical judgement and observations and often result in false positives (Sreenivasan, Kirkish, Garrick, Weinberger, & Phenix, 2000). “The abundance of literature and consistent description of the violent offender suggests that those with certain characteristics are more likely to exhibit violent behaviour” (Galperin & Leck, 2007, p. 115).

Douglas, Ogloff, and Hart (2003) put forward that using a structured professional judgement model for risk assessment, along with the Historical, Clinical and Risk Management 20 (HCR-20) violence assessment scheme, in a collaborative fashion, has merit. The HCR-20 is a tool used to assess the risk for violence and acts of violence (Douglas, Ogloff, & Hart, 2003). Their findings support that use of the structured professional judgement model is concordant with the HCR-20. This study suggests that clinical judgement made within a structured context can contribute in meaningful ways to the assessment of violence risk (Douglas, Ogloff, & Hart, 2003, p. 1372.

Violence risk is of paramount concern to law enforce and public safety personnel in addition to mental health professionals. Predicting Officer Physicals Assaults in Domestic Assault Cases (Johnson, 2011) identifies "five significant batterer characteristics (i.e. employment status, shared residence with victim, alcohol consumption, property damage, and hostile demeanour towards officers) that successfully predicted officer assault" (p. 163). In addition to such characteristics as hostile demeanor, Matsumoto and Hwang (2014) also found that individuals do exhibit reliable facial signs of imminent aggression or violence. Understanding these concepts may result in better training for individuals in harm's way to be trained to identify signs of imminent danger before it occurs.

As an aside regarding attempts at predicting crime in general, Baradaram & McIntyre (2012), touch upon how judges often confine and lockup the wrong people in attempts to ferret out who is likely to commit crime on pre-trial release. “Judges often overhold older defendants, defendants with clean records, and defendants charged with fraud and public-order crimes” (p. 497). This not only underscores the challenges in predicting crime, let alone violent crime, but what happens when predictions are wrong.

Conclusion

The challenge of trying to predict the probability of violence behaviour involves a host of dynamic and static factors. The most predictive factor for violence is an individual's history of violence (Ackerman, 1999). The second most predictive factor is the individual's history of substance abuse (Ackerman, 1999). Monahan (1994) holds that the “assessment challenge is to estimate the number of factors currently in play and to estimate their roles in the future. It makes sense to consider both the actuarial (static) and clinical (dynamic) approaches when conducting violence risk assessments to predict the potential for violent behaviour.

Maximillian Wachtel (2012) observes that “psychologists are pretty bad at predicting the potential for violent behaviour,” but that they are getting better. Wachtel concisely summarizes what is known about risk assessment and predicting violence (p.1):

Psychologists used to be absolutely terrible at predicting future violence. We used to get it wrong two out of three times.

We have improved dramatically in this arena. We can accurately predict future violence about 65-70% of the time.

We are still not all that great at it. We get it wrong about one in three times.

The best current method for assessing the risk of future violence is by examining an individual's static risk factors (Wording in a risk assessment report might look something like this: "Based on a review of Mr. Jones' static risk factors, he is at moderate to high risk for engaging in a violent act sometime within the next seven years").

In order to assess for the risk of violence in the short-term (days to weeks), a review of both static and dynamic risk factors is important.

Nevertheless, the question, “How dangerous is it that this man goes loose?” remains a perplexing challenge for the courts, lawyers, mental health professionals, and the general public.

Dr. Devor has a BA in Economics (specializing in quantitative analysis) from San Diego State University, a master's Degree in Marriage and Family Therapy from Argosy University and a doctorate degree in Applied Clinical Psychology from The Chicago School of Professional Psychology at the Irvine, California campus.

She is currently doing her post-doctoral work as a clinical psychological assistant in Orange County, California. She guest lectures on behavioral emergencies for military and civilian college students at Palomar College. Her areas of interest are psychological trauma, especially, as related to military, law enforcement, and emergency services. She works with both personnel and their families.

Dr. Devor has served as a volunteer field operations representative in Ghana, Africa. She is a co-founder of Kindred Spirits, an organization founded to create an orphanage and school for street children with disabilities. In addition, she has traveled to Sierra Leone, working in a psycho-social children's camp, along with participating in field research on female genital mutilation/cutting and rehabilitation of child soldiers.

GI Wilson is a retired Marine Corps combat veteran with over 40 years of combined experience in military operations, law enforcement, and risk assessment. He is a board Certified Protection Professional (CPP), Certified Forensic Consultant (CFC), and Diplomate of the American Board of Forensic Examiners. He teaches in the Administration of Justice (AJ) Program (Homeland Security, Investigations, Law Enforcement) of Palomar College while serving as a North San Diego County Gang Commissioner. His areas of interest are criminal behavior, gangs, psychopathy, incarcerated military veterans, terrorism, and emerging threats. He holds an undergraduate degree in psychology from the State University of New York at Albany, master's degrees in Security Management from Webster University, and Forensic Psychology from Argosy University.